Tasmania, Australia, is a region famed for the prowess of its renewable energy sector. Although the solar PV sector has not quite lifted off, the same cannot be said for hydropower and wind energy.
Most of the state’s renewable energy supply comes from hydroelectric generation and storage schemes via pumped hydro energy storage (PHES), with Tasmania holding 27% of Australia’s total freshwater dam storage capacity. It has a capacity of more than 2,600MW and includes 30 power stations and more than 50 major dams.
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Alongside this, the island state gains significant contributions from Tasmanian wind farms, which benefit from the ‘Roaring Forties’, an area of the globe that continuously sees strong winds of around 15 to 30 knots all year round.
This abundance of natural resources has meant that Tasmania is already 100% self-sufficient in renewable electricity generation and has been net zero in six out of the last seven years.
But, despite this, the island state continues to expand its installed capacity, with further hydropower projects being touted for the state. This is to turn the state into the ‘Battery of the Nation’, with utility Hydro Tasmania having revealed in 2022 that it was exploring opportunities to develop a further 1,500MWh to 3,500MWh of PHES. This would provide dispatchable capacity in the National Electricity Market (NEM) through to 2040.
With this expansion plan for the island’s hydroelectric and renewable energy generation well underway, a focus has been on increasing interconnectivity between Tasmania and mainland Australia to allow this capacity to help decarbonise the National Electricity Market (NEM), which stretches across South Australia, Tasmania, Victoria, New South Wales, the Australian Capital Territory and Queensland.
Interconnectivity with mainland Australia
Tasmania is currently connected to mainland Australia and the NEM via a sole interconnector: Basslink. The Basslink interconnector is a 500MW high-voltage direct current (HVDC) interconnector stretching from the Loy Yang Power Station in Victoria, on the Australian mainland, to the George Town substation in northern Tasmania.
It is bi-directional, allowing energy to be transmitted both ways. This enables Tasmania’s abundance of hydroelectricity plants, and PHES to supply peak load capacity to the NEM.
Plans are also underway to develop another interconnector. Dubbed the Marinus Link, the project aims to construct a 1.5GW undersea HVDC interconnector between Victoria and Tasmania, with a completion date of 2030.
The interconnector, which will run between Northwest Tasmania and the Latrobe Valley in Victoria, will be 345km long and include 255km of undersea cables that will cross the Bass Strait. It will be split into two development stages, both of which will see 750MW installed.
Interconnectors such as Basslink and Marinus Link will be critical in ensuring that Tasmania can attain its ‘Battery of the Nation’ status, provide additional dispatchable services to the NEM, and increase the amount of renewable energy available to mainland Ausstralia.
This is a perspective that has been shared by Thomas Fitzsimons, a senior modeller at UK-based research group Cornwall Insight, who recently told Energy-Storage.news that the viability of PHES projects in Tasmania could “come into question” due to a lack of interconnectivity with mainland Australia.
Marinus Link ‘critical’ to Tasmania’s ‘Battery of the Nation’ plan
The Marinus Link’s role in supporting Tasmania’s increase in the amount of hydropower available on the NEM has attracted various admirers in the Australian energy market. One such admirer is Kane Thornton, CEO of the Clean Energy Council, who exclusively tells Energy-Storage.news that the project will be “critical” in turning Tasmania into the ‘Battery of the Nation’.
“Tasmania has around 100-years of hydropower experience, and I think that is becoming increasingly valuable to Victoria and other parts of mainland Australia. Currently there is a constraint, by virtue of network connection, and the Marinus Link is therefore really critical to strengthening that connection so that more hydropower can flow into Victoria during peak times,” Thornton says.
Thornton also outlines that although around AU$5 billion (US$3.26 billion) has been invested last year in “big batteries”, there is a need to diversify the forms of energy storage to include other long-duration technologies, such as PHES, which is ripe in Tasmania.
Thornton adds: “Pumped hydro and hydropower are great examples of technologies that will become more valuable.”
Developing the Marinus Link interconnector
Developing interconnectors is by no means easy, and in the case of the Marinus Link, all eyes are on the project to provide much-needed support and an influx of renewable energy into the NEM.
Mark Lindsay, engagement manager at Marinus Link Pty, the developer behind the project, tells Energy-Storage.news at All-Energy Australia 2024 that the project will help connect some of Tasmania’s “extraordinary” resources.
“The capacity of Tasmania’s hydro is 30,000 times that of Victoria’s ‘Big Battery’,” Lindsay says, highlighting the potential generation that the NEM could be unlocking through increased interconnectivity.
Like Thornton, Lindsay references using Tasmania’s hydropower to transmit renewable energy to mainland Australia. Thanks to the bi-directional nature of the interconnector, solar PV generation could also be sent to the island state.
“Marinus Link will enable that opportunity to be able to transmit that excess energy between the mainland and Tasmania, saving that energy for when it is most needed,” Lindsay says.
Despite the project’s potential, Lindsay quickly notes that the Marinus Link interconnector is still in its design and approvals phase, with hopes that the outcome of the environmental approvals process will be provided in the first quarter of 2025.
“That’s the work that we’ve been doing for several years for the Victorian, Tasmanian and Commonwealth regulators,” Lindsay says. “We are also aiming for a final investment decision on the project around the mid-way point of next year.”
Another crucial aspect of the project is securing “social licence”, which is regarded as securing public support for developing the Marinus Link which includes enabling infrastructure, such as the converter stations, in Victoria and Tasmania.
“Our approach to engaging with communities in Tasmania and Victoria is similar, and we are at different stages of connecting with our communities. In Gippsland, there’s feeling of a readiness regarding the transition to renewable energy sources and away from coal, of which Gippsland has been built and that the community is proud of,” Lindsay says.
“The move into renewable energy has been warmly welcomed, and we get a sense with projects like Marinus Link that people are asking: how can I find out more? How’s it progressing? Are there job opportunities, community, and benefit sharing?”
Lindsay explains that in Tasmania, Marinus Link is coniuing to connect with communities, mostly in the north west of the state, to help the residents fully understand the project and its benefits for the local communities and Tasmanian’s more broadly.
“We’ve still got plenty of work to do in Tasmania and Victoria but like many emerging energy projects, we are progressing steadily with a number of major milestones set for 2025.”
The technicalities behind the Marinus Link
Akin Olayiwola, senior converter engineer at Marinus Link, gave deeper insight into some of the technicalities of developing an interconnector in Australia. He revealed that Marinus Link will harness DC power transmission technology against the more conventional AC, with both having pros and cons.
“With DC power transmission, you do tend to get less electrical power losses along a long distance of power transmission,” Olayiwola explains. “With conventional AC, the losses will be so much after a certain distance that the infrastructure to accommodate that power transmission will become enormous. In that sense, that’s where DC technology comes online to mitigate those losses.”
AC is typically used across Australia and the globe when developing network infrastructure. With HVDC to be used in the Marinus Link, a key component of the project is the converter stations, which turn the transmitted electricity from the interconnector into AC to be used throughout the grid. For this, the project uses new technology.
“With Marinus Link, we’re using what we call ‘voltage source converters’. It’s a new technology that also gives us more advantages and more benefits in terms of DC power transmission,” Olayiwola says.
According to the European Network of Transmission System Operators for Electricity (ENTSO-E), voltage source converters are capable of self-commutation, generating AC voltages without the need to rely on an AC system. This allows for independent rapid control of both active and reactive power and black start capability.
However, despite the pros of using new technologies, such as voltage source converters and HVDC, which are fairly new to the Australian energy market, finding specialists has been challenging for the Marinus Link team.
“Getting us specialists on the technologies was a bit challenging, and most of the high energy suppliers of these technologies are located overseas, and considering the time difference, getting information back and forth is a big challenge. With the measures we’re already put in place, I think we’re overcoming these sorts of challenges,” Olayiwola states.
